WO2010150830A1 - Light-emitting device - Google Patents

Abstract

Disclosed is a light-emitting device which comprises a conductive layer for light reflection and has improved light extraction efficiency and excellent heat dissipation properties, said conductive layer for light reflection having a high optical reflectance that is not decreased much by corrosion. Specifically disclosed is a light-emitting device which comprises: a ceramic substrate which has a lower ceramic layer, a conductive layer for light reflection that is formed in a desired region on the surface of the lower ceramic layer, and an upper ceramic layer that is formed so as to cover at least a partial region of the conductive layer for light reflection; and a light-emitting element that is arranged on top of the upper ceramic layer of the ceramic substrate. The light-emitting device is characterized in that the upper ceramic layer has a thickness of 5-100 µm. The upper ceramic layer may be configured of a glass-ceramic material that contains, in mass%, 40-60% of a glass component and 40-60% of a ceramic filler component.

Description

Light emitting device

The present invention is a light emitting diode (hereinafter sometimes referred to as LED) device, a high brightness photodiode backlight, a light source associated with a display, an automotive lighting, decorative lighting, signage, advertising lighting, and lighting device including information display applications. The present invention relates to a light-emitting device in forming the substrate and a mounting substrate used therefor.

In recent years, with the increase in brightness and whiteness of light emitting devices such as LEDs, light emitting devices using LEDs have come to be used for backlights of mobile phones and large liquid crystal TVs. In order to apply the LED lamp to various uses, it is important to obtain white light emission.

As a method of realizing white light emission with an LED lamp, a method of using three LED chips that emit light of each color of blue, green and red, a method of combining a blue light emitting LED chip and a yellow or orange light emitting phosphor, Examples include a method of combining a blue light emitting LED and a phosphor that excites red and green by the light, a method of combining an ultraviolet light emitting LED chip and a three-color mixed phosphor of blue, green, and red light emission. As a method of combining an LED chip and a phosphor, a bullet-type structure in which a transparent resin such as an epoxy resin or a silicone resin mixed with a phosphor is poured and solidified to form a resin layer containing the phosphor is known. Yes. Also known is a structure in which an LED chip is mounted on a substrate having a wiring pattern formed on the main surface, and a sealing portion made of a transparent resin is formed on the substrate.

In the LED lamp, a light reflecting layer such as silver is formed on a substrate around the mounted LED chip. And by this light reflection layer, the light emission from the LED chip radiated to the substrate side and the fluorescence excited and emitted from the phosphor are reflected forward to improve the light extraction efficiency.

However, silver is easily corroded, and if left as it is, a compound such as Ag ₂ S is generated and the light reflectance is likely to be lowered. For this reason, a resin sealing layer is formed on silver to prevent a decrease in reflectivity. However, epoxy resins and silicone resins used as general sealants have low sealing performance and long-term reliability. It could not be used for products that require sex.
Therefore, a method of coating the surface of silver with a resin such as a silicone resin, an acrylic resin, an epoxy resin, or a urethane resin in order to prevent corrosion of the silver conductor layer (see Patent Document 1) has been proposed.

However, even if it is coated with resin, moisture or corrosive gas easily enters in the resin or from the interface between the silver conductor layer and the resin, and the silver conductor layer corrodes with time.

JP 2007-67116 A

In order to solve the above problem, the present inventor tried a method of coating the silver conductor layer on the surface of the substrate with a glass film (Japanese Patent Application No. 2008-212591). When the heat generated from the LED is inferior and the amount of heat generated by the LED is large, the voltage applied to the LED is lowered, the luminous efficiency is lowered, and the LED life is shortened.

An object of the present invention is to provide a light-emitting device that has high light reflectivity, little reduction in reflectivity due to corrosion, and improved light extraction efficiency.
Another object of the present invention is to suppress the process load as much as possible in the formation of such a light reflecting layer.

In order to solve the above problems, the invention corresponding to claim 1 includes a ceramic substrate having a hole so as to expose a part of the light reflecting conductor layer, and incorporating the light reflecting conductor layer, In the light emitting device having the light emitting element arranged to be conducted through the hole on the ceramic substrate, the thickness of the upper ceramic layer between the light emitting element arranging surface and the light reflecting conductor layer is 5 ˜100 μm.
According to a second aspect of the present invention, there is provided a lower ceramic layer, a light reflecting conductor layer formed in a desired region of the lower ceramic layer surface, and an upper ceramic layer formed to cover at least a partial region of the light reflecting conductor layer. And a light emitting device disposed above the upper ceramic layer of the ceramic substrate, wherein the upper ceramic layer has a thickness of 5 to 100 μm. .
The invention corresponding to claim 3 is the light emitting device according to claim 2, wherein an external electrode terminal is formed on the surface of the lower ceramic layer of the ceramic substrate opposite to the light emitting element, and the external electrode The terminal and the light reflecting conductor layer are electrically connected through a via conductor formed so as to penetrate the lower ceramic layer.

The invention corresponding to claim 4 is the light emitting device according to any one of claims 1 to 3, wherein the light emitting device is formed so as to include the light emitting element, and is excited by light emitted from the light emitting element. It has a sealing resin layer containing a phosphor that emits visible light.

The invention corresponding to claim 5 is the light emitting device according to any one of claims 1 to 4, wherein the upper ceramic layer is white.

The invention corresponding to claim 6 is the light emitting device according to any one of claims 1 to 5, wherein the upper ceramic layer is 40% to 60% glass component and 40% to 60% ceramic filler in mass%. It was composed of glass-ceramics containing the components.

The invention corresponding to claim 7 is the light emitting device of the invention corresponding to claim 6, wherein the ceramic filler component is alumina.

The invention corresponding to claim 8 is the light emitting device according to claim 6 or 7, wherein the glass component contains 62 to 85% of SiO ₂ and 5 to ₂ of B ₂ O ₃ in terms of mol% based on oxide. 25%, Al ₂ O ₃ 0 to 5%, Na ₂ O and one or more of K ₂ O in total 0 to 5%, and the total content of SiO ₂ and Al ₂ O ₃ is When at least one selected from the group consisting of 62 to 85%, MgO, CaO, SrO and BaO is contained, the total content is 10% or less.

The invention corresponding to claim 9 is the light emitting device of the invention corresponding to any one of claims 6 to 8, wherein the glass component is expressed by mol% on the basis of oxide, SiO ₂ is 78 to 82%, B ₂ O. ₃ to 16 to 18%, and at least one of Na ₂ O and K ₂ O is contained in a total amount of 0.9 to 4%.

The invention corresponding to claim 10 is the light emitting device according to any one of claims 1 to 9, wherein the upper ceramic layer is eluted when immersed in an oxalic acid solution having a pH of 1.68 at 85 ° C. for 1 hour. The amount was made of glass-ceramics of 100 μg / cm ² or less.
The ceramic substrate for a light-emitting device of the present invention is a ceramic substrate for a light-emitting device having a light-reflecting conductor layer that reflects light from a light-emitting element, and a lower ceramic layer and a light-reflecting conductor positioned on the lower ceramic layer. And an upper ceramic layer located on the light reflecting conductor layer and the lower ceramic layer, and an opening was formed in the upper ceramic layer located on the light reflecting conductor layer. The upper ceramic layer preferably has a thickness of 5 to 100 μm.
The hole in the invention corresponding to the first aspect means an opening formed in the upper ceramic layer so as to expose a part of the light-reflective conductor layer built in the ceramic substrate. A light emitting element is disposed on the upper ceramic layer, and a bonding wire connected to the light emitting element in the hole is conducted through the light reflective conductor layer.

In order to protect the light reflecting conductor layer, the present inventor has realized a light emitting device excellent in heat dissipation without reducing the reflectance by incorporating the light reflecting conductor layer in the ceramic substrate.
In the present specification, “˜” is used to mean that the numerical values described before and after the value are included as the lower limit value and the upper limit value unless otherwise specified.

In the light emitting device of the present invention, the light reflecting conductor layer having a very high light reflectance is formed on the main surface of the substrate, so that the light from the light emitting element radiated to the substrate side is high in the opening direction on the side opposite to the substrate. It can be reflected with reflectivity. As a result, the light extraction efficiency can be improved, and the light emission efficiency can be improved.

Further, it has a phosphor layer that emits visible light when excited by light from the light emitting element, and the visible light emitted from this phosphor layer is also high forward on the opposite side of the substrate by the light reflecting conductor layer. Since the light is reflected at the reflectance, it is possible to improve the extraction efficiency of white light due to color mixture of visible light emitted from the phosphor layer and light emitted from the light emitting element.
Further, an upper ceramic layer made of glass-ceramics with little light absorption is provided on the light reflecting conductor layer, and the lower light reflecting conductor layer is chemically protected by this layer. Therefore, corrosion of the light reflecting conductor layer is prevented, and a decrease in light reflectance is suppressed. In addition, the upper ceramic layer has a high thermal conductivity, and it is difficult to inhibit the heat dissipation of the LED chip, thereby preventing the light emission efficiency from being lowered and the life from being shortened.

It is an example of sectional drawing of the ceramic substrate which incorporates the light reflection conductor layer used for this invention. It is an example of sectional drawing of the light-emitting device of this invention. It is an example of sectional drawing of the light-emitting device of this invention which plated the conductor layer surface for light reflection.

As shown in FIGS. 2 and 3, the ceramic substrate 1 in the light emitting device of the present invention is formed of an upper ceramic layer 3, a light reflecting conductor layer 2, and a lower ceramic layer 10. A light emitting element 6 is disposed on the upper ceramic layer 3. An external electrode terminal 8 is formed on the surface of the ceramic substrate 1 opposite to the light emitting element 6 of the lower ceramic layer 10. The external electrode terminal 8 and the light reflecting conductor layer 2 penetrate through the lower ceramic layer 10. It is conducted through the formed via conductor 4. An opening hole 11 is formed in a desired portion of the upper ceramic layer 3, and a bonding wire 7 is connected to the opening hole 11, and the light emitting element 6 and the light reflecting conductor layer 2 are electrically connected via the bonding wire 7. Has been. In the figure, reference numeral 5 denotes a sealing resin layer that includes the light emitting element 6 and covers a desired region of the upper ceramic layer 3 and the light reflecting conductor layer 2. A phosphor that emits visible light when excited by light emitted from the element is contained.
In the example shown in FIG. 3, the light reflecting conductor corresponding to the exposed surface of the light reflecting conductor layer 2, that is, the portion where the upper ceramic layer 3 is not formed and the opening hole 11 is formed in the upper ceramic layer 3. A gold plating layer 9 is formed on the surface of a desired region of the layer 2 to prevent characteristic deterioration due to discoloration of the light reflecting conductor layer 2.
In the present invention, particularly excellent as the above-described light reflecting conductor layer is a silver conductor that functions as a conductor and has excellent light reflectivity. Hereinafter, the light reflecting conductor layer may be referred to as a silver conductor layer. The present invention will be described below with a representative example using such a silver conductor layer.

As described above, the light-emitting device of the present invention has a ceramic substrate (hereinafter sometimes referred to as a substrate of the present invention) containing a silver conductor layer on the substrate of the present invention so as to be electrically connected to the silver conductor layer. And a light emitting element arranged. Here, the board | substrate of this invention is formed from the upper ceramic layer, the light reflection conductor layer, and the lower ceramic layer.

The substrate of the present invention is a flat member on which a light emitting element is mounted, and has a silver conductor layer for reflecting light traveling downward from the light emitting element, that is, light traveling in the direction of arrow A in FIGS. It is characterized by that.

The upper ceramic layer of the substrate of the present invention is a layer for protecting the silver conductor layer from corrosion and the like, and preferably contains a glass component and a ceramic filler component. Typically, it is a LTCC (Low Temperature Co-fired Ceramics) substrate (low temperature co-fired laminated ceramic substrate). Since the upper ceramic layer of the substrate of the present invention contains a glass component, the sealing performance is high and the internal silver conductor layer can be sufficiently protected. Moreover, since the ceramic filler component is contained, the thermal conductivity is high. Moreover, since the thickness is as thin as 100 μm or less, the light reflected by the silver conductor layer is hardly absorbed, and a high reflectance can be obtained.

In the substrate of the present invention, the material constituting the lower ceramic layer is not particularly limited as long as it is a ceramic on which a silver conductor or the like can be baked, but it may be the above-described LTCC substrate from the viewpoint of thermal conductivity, heat dissipation, strength, and cost. preferable. LTCC is a ceramic that can be fired simultaneously with a silver conductor. If both the upper ceramic layer and the lower ceramic layer constituting the substrate of the present invention are LTCC, the upper ceramic layer, the lower ceramic layer, and the silver conductor layer are The integrated substrate of the present invention can be formed efficiently.

In the present invention, the light emitting element is an LED element, and includes a type that emits visible light by exciting a phosphor with emitted light. For example, a blue light emitting type LED chip and an ultraviolet light emitting type LED chip are exemplified. However, the present invention is not limited to these, and various light-emitting elements can be used depending on the application of the light-emitting device, the intended emission color, and the like.

The mounting of the light emitting element is, for example, a method in which the LED chip is bonded to the substrate with an epoxy resin or a silicone resin (die bonding), and the electrode on the upper surface of the chip is connected to the pad portion of the ceramic substrate via a bonding wire such as a gold wire. Alternatively, bump electrodes such as solder bumps, Au bumps, and Au—Sn eutectic bumps provided on the back surface of the LED chip are flip-chip connected to the lead terminals and pad portions of the ceramic substrate.

The phosphor is excited by the light emitted from the light emitting element to emit visible light, and the visible light or the visible light itself emitted from the phosphor by color mixing of the visible light and the light emitted from the light emitting element. As a light emitting device, a desired light emission color is obtained by mixing the colors. The type of the phosphor is not particularly limited, and is appropriately selected according to the intended emission color, light emitted from the light emitting element, and the like. The phosphor layer containing such a phosphor is formed by mixing and dispersing the phosphor in a transparent resin such as a silicone resin or an epoxy resin. The phosphor layer is formed so as to cover the outside of the light emitting element.

Hereinafter, although embodiment of this invention is described, this invention is not limited to these.
The lower ceramic layer of the substrate of the present invention is not particularly limited as long as it can be provided with a silver conductor layer and an upper ceramic layer (insulating layer) that protects the silver conductor layer. Hereinafter, the case where the entire substrate of the present invention is an LTCC substrate will be described. To do.

The LTCC substrate is a substrate that can be manufactured by firing at the same time as the silver conductor layer. The LTCC substrate is usually manufactured by baking glass powder and ceramic filler powder as a green sheet. That is, first, glass powder and alumina powder, resin such as polyvinyl butyral and acrylic resin, plasticizer such as dibutyl phthalate, dioctyl phthalate, butyl benzyl phthalate, solvent such as toluene, xylene, butanol, and dispersant Etc. are added to form a slurry, and this slurry is formed into a sheet by a doctor blade method or the like on a film of polyethylene terephthalate or the like. The sheet formed into a sheet is dried to remove the solvent to obtain a green sheet. If necessary, these green sheets are formed with wiring patterns, vias, etc. by screen printing using a silver paste, and usually a plurality of sheets are laminated and fired.

The method of forming the substrate of the present invention by LTCC is not limited. However, after the silver conductor that becomes the silver conductor layer is printed on the green sheet that becomes the lower ceramic layer later using the silver paste, another method that becomes the upper ceramic layer is obtained. A method of laminating and firing green sheets, a method of printing and firing a glass-ceramic paste serving as an upper ceramic layer on a green sheet serving as a lower ceramic layer printed with a silver conductor, and using a silver paste on a green sheet There is a method of printing and baking a glass-ceramic paste for forming a top ceramic layer after printing and firing a silver conductor.

The green sheet is processed into a desired shape and fired to form a substrate. In this case, the object to be fired is a stack of one or more identical green sheets. The calcination is typically performed at 850 to 900 ° C. for 20 to 60 minutes. More typically, the firing temperature is maintained at 860 to 880 ° C.
In addition, when forming a silver conductor layer, it is preferable that a calcination temperature is 880 degrees C or less. If it exceeds 880 ° C., silver or the silver-containing conductor may be softened during firing, and the shape of the conductor pattern may not be maintained. More preferably, it is 870 degreeC or less.

The thickness of the upper ceramic layer is preferably 5 to 100 μm. If the thickness is less than 5 μm, the surface of the silver conductor layer is rough, so that the light emitting element tends to tilt when the light emitting element is disposed, and the light extraction efficiency may be deteriorated. If it exceeds 100 μm, the heat dissipation of the light emitting element may be hindered and the light emission efficiency may be reduced. Alternatively, the light extraction efficiency may be deteriorated due to the absorption of light and the decrease in reflectance.

The upper ceramic layer of the substrate of the present invention is preferably composed of a glass-ceramic comprising a glass component and a ceramic filler component. The proportion of the ceramic filler component is 40 to 60% by mass, and the remainder is a glass component. A glass-ceramic having the glass of the present invention and a ceramic filler component described later in this proportion is hereinafter referred to as a first glass-ceramic.

The ceramic filler is mixed for the purpose of improving thermal conductivity, and a material having high thermal conductivity and low light absorption in the visible light region is preferable. Alumina is typically used. The mixing amount is 40 to 60% by mass when the total amount of the glass component and the ceramic filler component is 100. If it is less than 40%, the thermal conductivity does not increase, and the effect on heat dissipation is small. If it exceeds 60%, the sinterability may be impaired, and the silver conductor layer may not be sufficiently protected.

The upper ceramic layer of the substrate of the present invention preferably has little light absorption, and is preferably white.

The upper ceramic layer of the substrate of the present invention is formed, for example, by pasting first glass-ceramics, screen printing, and firing. Alternatively, it is formed by firing the first glass-ceramic as a green sheet. However, there is no particular limitation as long as it is a method that can typically form a flat film having a thickness of 5 to 100 μm.

The first glass - glass component contained in the ceramics, the SiO ₂ 62 ~ _85% by mol% based on _{oxides, B 2 O 3 5 ~ 25%} , the _{Al 2 O 3 0 ~ 5%} , Na A group of MgO, CaO, SrO and BaO, containing a total of 0 to 5% of any one or more of ₂ O and K ₂ O, and a total content of SiO ₂ and Al ₂ O ₃ of 62 to 85% In the case of containing at least one selected from the above, it is preferable that the total content of the glass is 10% or less (hereinafter referred to as the glass of the present invention).

The glass of the present invention is obtained by a melting method and is pulverized into glass powder. The method of pulverization is not limited as long as it does not impair the object of the present invention, and any of dry pulverization and wet pulverization can be appropriately employed. In the case of wet pulverization, it is preferable to use water as a solvent. For pulverization, a pulverizer such as a roll mill, a ball mill, or a jet mill can be appropriately used. After pulverization, the glass is dried and classified as necessary.

While such particle size and shape of the alumina is not particularly limited, typically those average particle diameter D ₅₀ of 1 5 [mu] m ~ is used. An example of such alumina is AL-47H manufactured by Showa Denko. The average particle diameter D ₅₀ of the herein refers to a value measured using a laser diffraction / scattering particle size distribution measuring apparatus.

The light reflecting conductor layer is preferably made of a silver conductor, and is preferably made of a silver alloy conductor. Examples of materials other than silver conductors include silver-palladium alloys and silver-platinum alloys. From the viewpoint of further increasing the reflectance of the light reflecting conductor layer, it is preferable that no other inorganic component is contained.

When the lower ceramic layer of the substrate of the present invention is made of LTCC, the second glass-ceramics constituting the lower ceramic layer and the first glass-ceramics constituting the upper ceramic layer may have the same composition.

Moreover, the glass of this invention can be used conveniently also for the glass selected as glass for forming a lower ceramic layer. In order to increase the strength of the LTCC substrate, the glass composition used for the second glass-ceramics for forming the lower ceramic layer is, for example, 57% to 65% SiO ₂ in terms of mol%, B ₂ O ₃ Is preferably 13 to 18%, Al ₂ O ₃ is 3 to 8%, CaO is 9 to 23%, and at least one of K ₂ O and Na ₂ O is contained in an amount of 0.5 to 6%. The ceramic filler is typically alumina.
In this case, the mixing ratio of the glass powder and the alumina powder is typically 40% by mass of the glass powder and 60% by mass of the alumina filler.

Next, the glass of the present invention will be described. In the following description, unless otherwise specified, the composition is expressed in mol% and is simply expressed as%.

SiO ₂ is a glass network former and is essential. If it is less than 62%, silver coloring tends to occur, and the reflectivity of the substrate may decrease. Preferably, it is 64% or more, more preferably 74% or more. If it exceeds 85%, the glass melting temperature becomes high, or the glass softening temperature (Ts) becomes high, and the necessary firing temperature may become high. Preferably, it is 84% or less, More preferably, it is 82% or less.

B ₂ O ₃ is a glass network former and is essential. If it is less than 5%, the glass melting temperature tends to be high, or Ts tends to be too high. Preferably, it is 10% or more, more preferably 12% or more. If it exceeds 25%, it is difficult to obtain stable glass, or the chemical durability may be lowered. Preferably, it is 22% or less, more preferably 18% or less.

Al ₂ O ₃ is not essential, but may be contained in a range of 5% or less in order to enhance the stability or chemical durability of the glass. If it exceeds 5%, yellow coloring (silver coloring) tends to occur when fired on a silver conductor. Preferably, it is 1% or less, more preferably 0.5% or less.

The total content of SiO ₂ and Al ₂ O ₃ is 62 to 85%. If it is less than 62%, chemical durability may be insufficient. Preferably, it is 64% or more, more preferably 74% or more. If it exceeds 85%, the glass melting temperature becomes high, or Ts becomes too high, which may make firing at low temperatures difficult. Preferably, it is 84% or less, More preferably, it is 82% or less.

Na ₂ O and K ₂ O are not essential, but are components that lower Ts, and can be contained up to 5% in total. If it exceeds 5%, chemical durability, particularly acid resistance, may be deteriorated, or the electrical insulation of the fired product may be deteriorated. Preferably, it is 4% or less, more preferably 3% or less. Moreover, it is preferable to contain 0.9% or more.

MgO, CaO, SrO and BaO are not essential, but may be contained up to 10% in total in order to reduce Ts or stabilize the glass. If it exceeds 10%, silver coloring tends to occur. Preferably, it is 7% or less in total, and more preferably 5% or less in total.
The glass of the present invention consists essentially of the above components, but may contain other components as long as the object of the present invention is not impaired. When such components are contained, the total content of these components is preferably 10% or less. However, lead oxide is not contained.

If you want to higher acid resistance of the upper ceramic layer, the glass of the present invention is a _{SiO 2 78 ~ 82%, B} 2 O 3 and 16 ~ 18%, Na ₂ O and _{K 2} O at least one agent In total (0.9 to 4%), Al ₂ O ₃ content of 0.5% or less, and CaO content of 1% or less (hereinafter referred to as glass A of the present invention). Is preferred.

Next, the composition of the glass A of the present invention will be described. The glass A of the present invention is the glass of the present invention, and is particularly preferable when the upper ceramic layer does not impair the reflection performance of the light reflecting conductor layer and it is desired to increase the reflectance.
SiO ₂ is a glass network former and is essential. If it is less than 78%, the chemical durability is lowered. Preferably it is 80% or more. If it exceeds 82%, the glass melting temperature tends to be high, or Ts tends to be too high.

B ₂ O ₃ is a glass network former and is essential. If it is less than 16%, the glass melting temperature tends to be high or Ts tends to be too high, and if it exceeds 18%, it is difficult to obtain stable glass, or the chemical durability may be lowered. Preferably it is 17% or less.

Al ₂ O ₃ is not essential, but may be contained in a range of 0.5% or less in order to enhance the stability or chemical durability of the glass. If it exceeds 0.5%, the glass melting temperature becomes high, or Ts becomes too high.

Na ₂ O and K ₂ O are components that lower Ts, and preferably contain at least one of them. If the total is less than 0.9%, the glass melting temperature may be high or Ts may be too high, preferably 1.0% or more, more preferably 1.5% or more. If it exceeds 4%, chemical durability, particularly acid resistance, may be deteriorated, or the electrical insulation of the fired product may be deteriorated. Preferably it is 3% or less, More preferably, it is 2% or less.

CaO is not essential, but may be contained in a range of 1% or less in order to lower Ts or stabilize the glass. If it exceeds 1%, the glass melting temperature becomes too low, or crystallization is promoted and a transparent glass layer cannot be obtained. Preferably it is 0.6% or less.
The glass A of the present invention consists essentially of the above components, but may contain other components as long as the object of the present invention is not impaired. When such components are contained, the total content of these components is preferably 10% or less. However, lead oxide is not contained.

A green sheet for forming the lower ceramic layer was produced by the following method. That is, in terms of mol%, SiO ₂ is 60.4%, B ₂ O ₃ is 15.6%, Al ₂ O ₃ is 6%, CaO is 15%, K ₂ O is 1%, Na ₂ O is 2 Glass raw materials were prepared and mixed so as to have a composition of%, and the mixed raw materials were put in a platinum crucible and melted at 1550 to 1600 ° C. for 60 minutes, and then the molten glass was poured out and cooled. The obtained glass was pulverized in ethyl alcohol using an alumina ball mill for 20 to 60 hours to obtain a glass powder. The _{D 50} of the powder was 2.5μm was measured using a Shimadzu Corporation SALD2100. When the softening point Ts (unit: ° C.) and the crystallization peak temperature Tc (unit: ° C.) were measured up to 1000 ° C. at a heating rate of 10 ° C./min using a thermal analyzer TG-DTA2000 manufactured by Bruker AXS. , Ts was unclear and Tc was 850 ° C.
An organic solvent (toluene, xylene, 2-propanol, 2-butanol is used in a mass ratio of 4: 2 to 50 g of powder obtained by mixing 40% of the glass powder and 60% of alumina powder AL-45H manufactured by Showa Denko KK in mass%. : 2: 1 mixed) 15 g, plasticizer (di-2-ethylhexyl phthalate) 2.5 g, resin (Denka Polyvinyl Butyral PVK # 3000K) 5 g and dispersant (Bicchemy DISPERBYK180) were mixed. To make a slurry. This slurry was applied onto a PET film using a doctor blade method and dried to obtain a green sheet for forming a lower ceramic layer having a thickness of 0.2 mm. For Examples 1 to 18, a lower ceramic layer was formed using this green sheet.

(Examples 1 to 18)
A glass-ceramic paste for forming the upper ceramic layer was produced by the following method. That is, as shown in each example of Table 1 to Table 3, raw materials are prepared and mixed so as to have a composition represented by mol% in the columns from SiO ₂ to ZrO ₂ , and the mixed raw materials are put in a platinum crucible. After melting at 1550-1600 ° C. for 60 minutes, the molten glass was poured out and cooled. The obtained glass was pulverized in ethyl alcohol for 20 to 60 hours using an alumina ball mill to obtain glass powder in the same manner as described above. D ₅₀ (unit: μm) of each glass powder obtained was measured using SALD2100 manufactured by Shimadzu Corporation. Further, the softening point Ts (unit: ° C.) and the crystallization peak temperature Tc (unit: ° C.) were measured up to 1000 ° C. at a temperature rising rate of 10 ° C./min using a Bruker AXS thermal analyzer TG-DTA2000. did. The respective values of D ₅₀ (unit: μm), softening point Ts (unit: ° C), and crystallization peak temperature (Tc unit: ° C) measured for the glass powder of each composition are shown in the respective columns of Tables 1 to 3. . What is described as “unclear” in the column of Ts is that the inflection point indicating Ts is unclear. In the column of “Tc”, “∞” indicates that no crystal peak was observed by 1000 ° C.

Each glass powder and alumina powder AL-45H were mixed to obtain a glass-ceramic mixed powder in which the content of the alumina powder was in the ratio indicated by mass% in the filler addition amount column of Tables 1 to 3. In a mass% display, 60% of each mixed powder, 40% of an organic vehicle prepared by mixing ethyl cellulose and α-terpineol in a mass ratio of 85:15, kneaded in a porcelain mortar for 1 hour, and further in three rolls A glass-ceramic paste was prepared by dispersing three times. Examples 1 to 11 are examples of the glass-ceramics of the present invention. Examples 1 to 7 are examples of the glass-ceramics of the present invention using the glass of the present invention.

(Production and evaluation of ceramic substrates)
Silver powder (S400-2 manufactured by Daiken Chemical Industry Co., Ltd.) and the above organic vehicle are mixed at a mass ratio of 85:15, kneaded for 1 hour in a porcelain mortar, and further dispersed using a three-roll mill. A paste was prepared.

The above-mentioned silver paste is printed on 6 green sheets for forming the lower ceramic layer, and after drying, each glass-ceramic paste for forming the upper ceramic layer of Examples 1 to 18 is printed on the silver paste. This was held at 550 ° C. for 5 hours to decompose and remove the resin component, then held at 870 ° C. for 30 minutes and baked, and as shown in FIG. 1, the lower ceramic layer 10, the silver conductor layer 2 and the upper portion A ceramic substrate (LTCC substrate) 1 in which a ceramic layer was laminated and the silver conductor layer 2 was built up to the end thereof was obtained.

The reflectance of the main surface of each LTCC substrate 1 is measured using a spectroscope USB2000 of Ocean Optics and a small integrating sphere ISP-RF, and the average value of 400 to 800 nm in the visible light region is taken as the reflectance (unit:%). Calculated. The results are shown in Tables 1 to 3. The reflectance is preferably 90% or more, and the higher the reflectance.

The acid resistance of the upper ceramic layer was evaluated by the following method. That is, 4 g of the glass-ceramic mixed powder was pressed with a die and fired to obtain a sintered body having a diameter of about 14 mm and a height of about 1.5 cm. It was immersed in 700 cm ³ of oxalate buffer and the mass loss after 1 hour was measured. In addition, the mass after immersion was performed after drying at 100 degreeC for 1 hour. The mass loss per unit surface area of the fired body (unit: μg / cm ² ) is shown in the acid resistance column of Tables 1 to 3. The acid resistance is preferably 100 μg / cm ² or less, more preferably 30 μg / cm ² or less. If it exceeds 100 μg / cm ² , components in the glass may elute in the plating solution and continuous operation may not be possible, or the upper ceramic layer may be eroded and light absorption may be increased.

The heat dissipating property was measured using a thermal resistance measuring instrument (model: TH-2167) manufactured by Guangyueon Electric Co., Ltd. Four LED chips, GQ2CR460Z from Showa Denko KK were connected in series, and KE-3000-M2 from Shin-Etsu Chemical Co., Ltd. was used as the die bond material. As the sealant, SCR-1016A manufactured by Shin-Etsu Chemical Co., Ltd. was used. The applied current was set to 35 mA, current was applied until the voltage drop saturated, and the saturation temperature Tj (° C.) was calculated from the temperature coefficient derived from the temperature-voltage drop characteristics of the LED chip. The saturation temperature is preferably less than 50 ° C, more preferably 45 ° C or less. When the temperature is higher than 50 ° C., the voltage drop becomes large, and the light extraction efficiency of the LED chip may be deteriorated or the life may be shortened.

According to the present invention, it is possible to obtain a light-emitting device that has high light reflectivity, little reduction in reflectivity due to corrosion, and improved light extraction efficiency. Such a light-emitting device can be a mobile phone, a large liquid crystal TV, or the like. It can be suitably used for various backlights and various lighting devices.
It should be noted that the entire contents of the specification, claims, drawings and abstract of Japanese Patent Application No. 2009-148577 filed on June 23, 2009 are incorporated herein by reference. .

1: ceramic substrate (LTCC substrate), 2: light reflecting conductor layer (silver conductor layer, conductor layer), 3: upper ceramic layer, 4: via conductor, 5: sealing resin layer (with phosphor), 6: Light emitting element, 7: bonding wire, 8: external electrode terminal, 9: gold plating, 10: lower ceramic layer, 11: opening hole

Claims (14)

A light emitting element provided with a hole so as to expose a part of the light reflecting conductor layer, a ceramic substrate containing the light reflecting conductor layer, and a conductive element disposed on the ceramic substrate through the hole. A light emitting device having a thickness of 5 to 100 μm of an upper ceramic layer between the light emitting element arrangement surface and the light reflecting conductor layer. A ceramic substrate having a lower ceramic layer, a light-reflecting conductor layer formed in a desired region of the surface of the lower ceramic layer, and an upper ceramic layer formed covering at least a partial region of the light-reflecting conductor layer; A light-emitting device comprising: a light-emitting element disposed on an upper ceramic layer of a substrate; wherein the upper ceramic layer has a thickness of 5 to 100 μm. An external electrode terminal is formed on the surface of the lower ceramic layer of the ceramic substrate opposite to the light emitting element, and the external electrode terminal and the light reflecting conductor layer are formed through the lower ceramic layer. The light emitting device according to claim 2, wherein the light emitting device is electrically connected via a via conductor. The sealing resin layer including a phosphor that is formed so as to include the light emitting element and that is excited by light emitted from the light emitting element and emits visible light. The light-emitting device of description. The light emitting device according to any one of claims 1 to 4, wherein the upper ceramic layer is white. The upper ceramic layer is made of glass-ceramics containing 40 to 60% glass component and 40 to 60% ceramic filler component by mass%. Light-emitting device. The light-emitting device according to claim 6, wherein the ceramic filler component is alumina. The glass component is expressed in terms of mol% based on oxide, and SiO ₂ is 62 to 85%, B ₂ O ₃ is 5 to 25%, Al ₂ O ₃ is 0 to 5%, Na ₂ O and K ₂ O. 1 to 5% in total, and the total content of SiO ₂ and Al ₂ O ₃ is 62 to 85%, at least one selected from the group consisting of MgO, CaO, SrO and BaO. The light-emitting device according to claim 6 or 7, wherein, if contained, the total content is glass of 10% or less. The glass component is expressed in mol% on the basis of oxide, and SiO ₂ is 78 to 82%, B ₂ O ₃ is 16 to 18%, and any one or more of Na ₂ O and K ₂ O is 0.9 in total. The light-emitting device according to any one of claims 6 to 8, which is contained in an amount of -4%. 10. The upper ceramic layer is made of glass-ceramic having an elution amount of 100 μg / cm ² or less when immersed in an oxalic acid solution having a pH of 1.68 at 85 ° C. for 1 hour. Light-emitting device. In a ceramic substrate for a light-emitting device having a light-reflecting conductor layer that reflects light from a light-emitting element, a lower ceramic layer, a light-reflecting conductor layer positioned on the lower ceramic layer, the light-reflecting conductor layer, and the A ceramic substrate for a light emitting device, comprising: an upper ceramic layer positioned on a lower ceramic layer; and an opening hole formed in the upper ceramic layer positioned on the light reflecting conductor layer. 12. The ceramic substrate for a light-emitting device according to claim 11, wherein the upper ceramic layer has a thickness of 5 μm to 100 μm. 13. The upper ceramic layer and the lower ceramic layer are composed of glass-ceramics containing 40 to 60% glass component and 40 to 60% ceramic filler component in mass%. Ceramic substrate for light emitting devices. The glass component is expressed in terms of mol% on the basis of oxide, and SiO ₂ is 62 to 85%, B ₂ O ₃ is 5 to 25%, Al ₂ O ₃ is 0 to 5%, Na ₂ O and K ₂ O. 1 to 5% in total, containing at least one selected from the group consisting of MgO, CaO, SrO and BaO, the total content of SiO ₂ and Al ₂ O ₃ being 62 to 85% The ceramic substrate for a light-emitting device according to claim 13, wherein the total content is 10% or less glass.

Images